Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review A

Two-photon cooling of magnesium atoms

Nicola Malossi, S. Damkjær, P. L. Hansen, L. B. Jacobsen, L. Kindt, Sébastien Sauge, Jan W. Thomsen, Flávio C. Cruz, M. Allegrini, E. Arimondo

Published Nov 16, 2005• 27 citations
Publisher

Abstract

A two-photon mechanism for cooling atoms below the Doppler temperature is analyzed. We consider the magnesium ladder system $(3{s}^{2})^{1}S_{0}\ensuremath{\rightarrow}(3s3p)^{1}P_{1}$ at $285.2\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ followed by the $(3s3p)^{1}P_{1}\ensuremath{\rightarrow}(3s3d)^{1}D_{2}$ transition at $880.7\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. For the ladder system quantum coherence effects may become important. Combined with the basic two-level Doppler cooling process this allows for reduction of the atomic sample temperature by more than a factor of 10 over a broad frequency range. First experimental evidence for the two-photon cooling process is presented and compared to model calculations. Agreement between theory and experiment is excellent. In addition, by properly choosing the Rabi frequencies of the two optical transitions a velocity independent atomic dark state is observed.

DOI
10.1103/physreva.72.051403

Related papers

Two-photon cooling of calcium atoms

Wojciech Adamczyk, Silvan Koch, Claudia Politi +6 more

We demonstrate cooling of calcium atoms using a two-photon transition from the ${}^{1}{S}_{0}$ ground state to the upper $4s5s\phantom{\rule{3.33333pt}{0ex}}{}^{1}{S}_{0}$ state via the ${}^{1}{P}_{1}$ intermediate state. We achieve temperatures as low as $260\phantom{\rule{0.16em}{0ex}}\textmu{}\mathrm{K}$ in a magnetooptical trap (MOT), well below the Doppler limit (${T}_{\text{D}}=0.8\phantom{\rule{0.16em}{0ex}}\mathrm{m}\mathrm{K}$) of the ${}^{1}{P}_{1}$ state. We characterize the temperature, lifetime, and confinement of the MOT over a range of experimental parameters, observing no reduction in lifetime due to coupling to the higher state. We perform theoretical simulations of the cooling scheme and observe good agreement with the experimental results. The two-photon cooling scheme presented in this work provides an alternative to the standard Doppler cooling applied to alkaline-earth atoms, based on a sequence of two magnetooptical traps. The advantages of our scheme are the possibility of varying the effective linewidth of the ${}^{1}{P}_{1}$ state, a higher transfer efficiency (close to $100%$), and a more straightforward experimental implementation.

arXiv:2411.16402•Physical Review A•Apr 1, 2025•2 citations

Investigations of a two-level atom in a magneto-optical trap using magnesium

F. Y. Loo, Anders Brusch, Sébastien Sauge +4 more

Magnesium atoms are cooled in a magneto-optical trap (MOT) using the 3s2 S0 → 3s3p P1 resonance transition. Magnesium is a simple atom which offers a unique possibility for comparison to the Doppler theory of laser cooling. We measure trap parameters as a function of laser-intensity, -detuning and magnetic field gradient. We find the main features well accounted for by Doppler theory, but temperature measurements gave significant higher values than predicted by the Doppler theory. We also observe radiation pressure effects within the MOT that limit the maximum achievable density. Comparing our results to predictions by models in the literature shows a good agreement. Recently we have improved our set-up and now trap about 150 × 106 atoms.

Journal of Optics B Quantum and Semiclassical Optics•Nov 7, 2003•3 citations

Two-photon Doppler cooling of alkaline-earth-metal and ytterbium atoms

Wictor C. Magno, Reinaldo L. Cavasso Filho, Flávio C. Cruz

The possibility of laser cooling of alkaline-earth-metal atoms and ytterbium atoms using a two-photon transition is analyzed. We consider a ${}^{1}{S}_{0}{\ensuremath{-}}^{1}{S}_{0}$ transition with excitation in near resonance with the ${}^{1}{P}_{1}$ level. This greatly increases the two-photon transition rate, allowing an effective transfer of momentum. The experimental implementation of this technique is discussed and we show that for calcium, for example, two-photon cooling can be used to achieve a Doppler limit of $123\ensuremath{\mu}\mathrm{K}.$ The efficiency of this cooling scheme and the main loss mechanisms are analyzed.

arXiv:physics/0303042•Physical Review A•Apr 22, 2003•31 citations

Temperature limits in laser cooling of free atoms with three-level transitions

Flávio C. Cruz, Michael Lee Sundheimer, Wictor C. Magno

Summary form only given. We consider laser cooling of free atoms with simultaneous two-color excitation of three-level cascade transitions [1], [2], [3], [4], [5], [6] finding theoretically that temperatures below the Doppler limits associated with each one of the individual transitions are obtained. We use standard laser cooling analysis [7], [8] and the dressed state picture in order to identify different cooling regions, and determining optimum parameters for guiding further experiments. These new “sub-Doppler” limits are reached at the two-photon resonance where a significant increase of the damping coefficient and decrease of the diffusion take place. In the dressed state picture, this point corresponds to a crossing of the narrow and a (partially) dark state.Figure 1 shows a plot of temperature (normalized to the Doppler limit for cooling only on the lower transition) as function of single-photon detunings, for the 1S0-1P1-1D2 transition of Magnesium, in which the lower 1S0-1P1 transition is the usual cooling one (λ1 = 2πc/ω1 = 285 nm, λ2 = 2πc/ω2 = 881 nm, γ1 = 2π 78.8 MHz, γ2 = 2π 2.2 MHz). A minimum temperature of 38 μK is predicted. This temperature is lower than the Doppler temperature of the lower and upper transitions, TD = γ/k = 1.9 mK and 49 μK respectively. Due to the asymmetric absorption profile of the dressed atom, there is a remarkable increase in the damping coefficient (α) associated with the narrow transition, in comparison with the broad transition (two-level cooling). The cooling and damping times, inversely proportional to α, are reduced by the same amount. Since the curve for the diffusion coefficient (D) has the same shape as the curve for the absorption coefficient or the population of the intermediate state, D is also reduced with respect to the broad resonance, We analyze situations previously implemented experimentally in alkaline-Earth atoms using cascade transitions, and also discuss prospects for Aand V-type three-level systems.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•May 1, 2013•0 citations

Ultracold Magnesium

Ernst Maria Rasel

We report on progress of generating ultracold atoms of magnesium. Magnesium belongs to the few elements suited for a neutral atom optical frequency standard. Its unique properties such as a very low black body radiation shift, the occurrence of fermionic and bosonic isotopes of suitable abundance, and the existence of a magic wavelength make it a very attractive candidate for future optical clocks. With our experiment, we determined for the first time the absolute frequency of the intercombination transition 31S0? 33P1of24Mg with a Ramsey-Bord Enterferometer, which was linked to a primary Cs Frequency standard of the PTB via a fiber femtosecond laser. Cooling ensembles of magnesium in the non-magnetic ground state to microkelvins is difficult as standard sub-Doppler cooling schemes are not applicable. We investigate novel methods to lower the temperatures of magnesium atoms. One promising method is based on a coherent two photon-process which provides higher velocity selectivity. Alternatively, standard sub-Doppler cooling schemes are applicable to the long-lived excited state, which in addition can be confined in magnetic traps. Article not available.

Quantum-Atom Optics Downunder (QAO)•Jan 1, 2007•0 citations

Two-photon cooling below the Doppler limit in bosonic magnesium

Matthias Riedmann, Karsten Moldenhauer, T. E. Mehlstäubler +6 more

Standard sub-Doppler cooling methods are not applicable in bosonic magnesium due to the non-degenerate ground state. However, the Doppler limit can be surpassed by coupling the excited state of the cooling transition to the level1D2and cooling via a coherent two-photon transition. This process modifies the population in1P1, similar to electromagnetically induced transparency, as well as the resulting force profile in optical molasses. These modifications can be used to obtain a steeper slope in the force profile around v=0 and hence lower temperatures as compared to doppler cooling on the strong transition only.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 1, 2007•0 citations
A two-photon mechanism for cooling atoms below the Doppler temperature is analyzed. We consider the magnesium ladder system (3s2)1S0\ensuremath→(3s3p)1P1(3{s}^{2})^{1}S_{0}\ensuremath{\rightarrow}(3s3p)^{1}P_{1}(3s2)1S0​\ensuremath→(3s3p)1P1​ at 285.2nm285.2\phantom{\rule{0.3em}{0ex}}\mathrm{nm}285.2nm followed by the (3s3p)1P1\ensuremath→(3s3d)1D2(3s3p)^{1}P_{1}\ensuremath{\rightarrow}(3s3d)^{1}D_{2}(3s3p)1P1​\ensuremath→(3s3d)1D2​ transition at 880.7nm880.7\phantom{\rule{0.3em}{0ex}}\mathrm{nm}880.7nm. For the ladder system quantum coherence effects may become important. Combined with the basic two-level Doppler cooling process this allows for reduction of the atomic sample temperature by more than a factor of 10 over a broad frequency range. First experimental evidence for the two-photon cooling process is presented and compared to model calculations. Agreement between theory and experiment is excellent. In addition, by properly choosing the Rabi frequencies of the two optical transitions a velocity independent atomic dark state is observed.
We demonstrate cooling of calcium atoms using a two-photon transition from the 1S0{}^{1}{S}_{0}1S0​ ground state to the upper 4s5s1S04s5s\phantom{\rule{3.33333pt}{0ex}}{}^{1}{S}_{0}4s5s1S0​ state via the 1P1{}^{1}{P}_{1}1P1​ intermediate state. We achieve temperatures as low as $260\phantom{\rule{0.16em}{0ex}}\textmu{}\mathrm{K}$ in a magnetooptical trap (MOT), well below the Doppler limit (TD=0.8mK{T}_{\text{D}}=0.8\phantom{\rule{0.16em}{0ex}}\mathrm{m}\mathrm{K}TD​=0.8mK) of the 1P1{}^{1}{P}_{1}1P1​ state. We characterize the temperature, lifetime, and confinement of the MOT over a range of experimental parameters, observing no reduction in lifetime due to coupling to the higher state. We perform theoretical simulations of the cooling scheme and observe good agreement with the experimental results. The two-photon cooling scheme presented in this work provides an alternative to the standard Doppler cooling applied to alkaline-earth atoms, based on a sequence of two magnetooptical traps. The advantages of our scheme are the possibility of varying the effective linewidth of the 1P1{}^{1}{P}_{1}1P1​ state, a higher transfer efficiency (close to 100100%100), and a more straightforward experimental implementation.
Magnesium atoms are cooled in a magneto-optical trap (MOT) using the 3s2 S0 → 3s3p P1 resonance transition. Magnesium is a simple atom which offers a unique possibility for comparison to the Doppler theory of laser cooling. We measure trap parameters as a function of laser-intensity, -detuning and magnetic field gradient. We find the main features well accounted for by Doppler theory, but temperature measurements gave significant higher values than predicted by the Doppler theory. We also observe radiation pressure effects within the MOT that limit the maximum achievable density. Comparing our results to predictions by models in the literature shows a good agreement. Recently we have improved our set-up and now trap about 150 × 106 atoms.
The possibility of laser cooling of alkaline-earth-metal atoms and ytterbium atoms using a two-photon transition is analyzed. We consider a ${}^{1}{S}_{0}{\ensuremath{-}}^{1}{S}_{0}$ transition with excitation in near resonance with the 1P1{}^{1}{P}_{1}1P1​ level. This greatly increases the two-photon transition rate, allowing an effective transfer of momentum. The experimental implementation of this technique is discussed and we show that for calcium, for example, two-photon cooling can be used to achieve a Doppler limit of $123\ensuremath{\mu}\mathrm{K}.$ The efficiency of this cooling scheme and the main loss mechanisms are analyzed.
Summary form only given. We consider laser cooling of free atoms with simultaneous two-color excitation of three-level cascade transitions [1], [2], [3], [4], [5], [6] finding theoretically that temperatures below the Doppler limits associated with each one of the individual transitions are obtained. We use standard laser cooling analysis [7], [8] and the dressed state picture in order to identify different cooling regions, and determining optimum parameters for guiding further experiments. These new “sub-Doppler” limits are reached at the two-photon resonance where a significant increase of the damping coefficient and decrease of the diffusion take place. In the dressed state picture, this point corresponds to a crossing of the narrow and a (partially) dark state.Figure 1 shows a plot of temperature (normalized to the Doppler limit for cooling only on the lower transition) as function of single-photon detunings, for the 1S0-1P1-1D2 transition of Magnesium, in which the lower 1S0-1P1 transition is the usual cooling one (λ1 = 2πc/ω1 = 285 nm, λ2 = 2πc/ω2 = 881 nm, γ1 = 2π 78.8 MHz, γ2 = 2π 2.2 MHz). A minimum temperature of 38 μK is predicted. This temperature is lower than the Doppler temperature of the lower and upper transitions, TD = γ/k = 1.9 mK and 49 μK respectively. Due to the asymmetric absorption profile of the dressed atom, there is a remarkable increase in the damping coefficient (α) associated with the narrow transition, in comparison with the broad transition (two-level cooling). The cooling and damping times, inversely proportional to α, are reduced by the same amount. Since the curve for the diffusion coefficient (D) has the same shape as the curve for the absorption coefficient or the population of the intermediate state, D is also reduced with respect to the broad resonance, We analyze situations previously implemented experimentally in alkaline-Earth atoms using cascade transitions, and also discuss prospects for Aand V-type three-level systems.
We report on progress of generating ultracold atoms of magnesium. Magnesium belongs to the few elements suited for a neutral atom optical frequency standard. Its unique properties such as a very low black body radiation shift, the occurrence of fermionic and bosonic isotopes of suitable abundance, and the existence of a magic wavelength make it a very attractive candidate for future optical clocks. With our experiment, we determined for the first time the absolute frequency of the intercombination transition 31S0? 33P1of24Mg with a Ramsey-Bord Enterferometer, which was linked to a primary Cs Frequency standard of the PTB via a fiber femtosecond laser. Cooling ensembles of magnesium in the non-magnetic ground state to microkelvins is difficult as standard sub-Doppler cooling schemes are not applicable. We investigate novel methods to lower the temperatures of magnesium atoms. One promising method is based on a coherent two photon-process which provides higher velocity selectivity. Alternatively, standard sub-Doppler cooling schemes are applicable to the long-lived excited state, which in addition can be confined in magnetic traps. Article not available.
Standard sub-Doppler cooling methods are not applicable in bosonic magnesium due to the non-degenerate ground state. However, the Doppler limit can be surpassed by coupling the excited state of the cooling transition to the level1D2and cooling via a coherent two-photon transition. This process modifies the population in1P1, similar to electromagnetically induced transparency, as well as the resulting force profile in optical molasses. These modifications can be used to obtain a steeper slope in the force profile around v=0 and hence lower temperatures as compared to doppler cooling on the strong transition only.